I just upgraded from my 40+ gallon to a 55 gallon tank, even do everytime i get a new tank I keep on saying myself that this is gonna be the last time!
so right now in my 55 gallon there is
9 albino cories
3 spotted cories
3 south american bumblebee catfish
6 platies and 1 male betta that is gonna be moved to a 5 gallon tank
so my questions are:
How many females in the tank?
Do they all have to be the same type of betta(halfmoon, veil tail, crown tail, etc..)?
Put them all at the same time or one by one?

Okay. I would recommend planting it like this, with Around 25-30 females. And adding them at different times as adding them all at once could end up in water quality disaster. While your tank can easily hold more females bio load wise. They still prefer there own space and don't like being packed to the full end stocking with sororities